Unable to install office - Error 25004

Thanks in advance for any help.

I recently purchased Office Ultimate 2007 Home and Student. Installation
goes fine until half way through where the install wizard stops and the
following error message appears:

Error 25004 - Config.xml not specified. Valid config.xml file must be
authored when deploying '(null)'

The installer then rolls back the changes made.

I have read several posts which mention this issue and have followed all
advice to no effect. I have manually uninstalled all office products
currently on my system to ensure there are no conflicts.

Does anyone have any idea how to fix this issue? Thanks!